Superfund Research Program
Sentinel Species: Xenobiotics, Toxicity, and Reproduction
Project Leader: Ian P. Callard
Grant Number: P42ES007381
Funding Period: 1995 - 2000
This project has investigated the turtles (Chrysemys picta) at a test site potentially impacted by xenobiotics from the Massachusetts Military Reservation on Cape Cod. Results from the research confirmed significant reproductive deficits (delayed maturity, a reduced cohort of early [1.0 - 5.0mm] follicles in females, reduced ovarian and oviduct weights, reduced plasma vitellogenin and estradiol levels, and reduced testis weight in males). These differences can be correlated with significantly increased tissue heavy metal load, increased hepatic p450 1A1 and glutathione-s-transferase and metallothionein levels in these same animals compared to those from the control site on Cape Cod. Cadmium is the heavy metal most significantly elevated in both kidney and liver of animals from the impacted site. Elevations in tissue cadmium load have also been seen in fresh water mussels (Elliptio complanata) from the same area. Renal concentrations of other metals (nickel, zinc) and hepatic lead were also highest at the impacted site. The results suggest that heavy metals, notably cadmium, may be interacting with organic xenobiotics at several sites in the hypothalamic-gonadal-pituitary-liver axis, possibly through nuclear hormone receptors, to bring about the suite of changes observed. Continuing research will determine the locus/loci of action of the contaminants by comparing responses of selected end-points (steroidogenesis, gametogenesis, hepatic vitellogenin and metallothionein synthesis, biotransformation enzymes, reproductive tract and liver steroid receptors) to hormonal stimuli in animals from the control and impacted sites.